My question relates more to the possibilities of life on Mars than to mining mineral deposits. QUESTION: Is it possible to have oxidized iron in the quantities that we see on Mars with only available free oxygen molecules, and without the existence of huge quantities of O2? I am trying to determine the possibility of the existence of "stromatolite" types of life early on in the life of Mars, whereas a parallel to Earth's life origins may have existed. I simply do knot know if the existence of "free oxygen" in lesser quantities than mass photosynthesized O2 is enough to rust out the entire planet. The existence of iron deposits in early oceanic seabeds may provide the best evidence of this, but I have yet to hear of any discovery of layered iron deposits. Thank you for your time and consideration.
Yes, it is possible for Mars to have a surface pretty much entirely oxidized even with the current low O2 levels (around 0.16 % ) in its atmosphere. Higher O2 levels would be necessary to oxidize surface if O2 sinks continued to show up on Mars's surface, but this does not occur on Mars because it is dry and little erosion occurs (yes there are storms, but these are not powerful enough for strong enough erosion). Therefore low O2 levels can oxidize the surface slowly since itself is very slowly changing.
Also, Mar's O2 levels were higher in the past. Due to Mars' small size, it slowly loses its Oxygen to space via ion recombination reactions in Mar's ionosphere. this reaction can be shown as: O2+ + e --> O + O these O's then have enough energy to escape Mar's weak gravity. Thus levels of O2 are predicted to be greater in Early Mars. This makes it more likely that the oxidation of the surface occurred in Early Mars. And since the surface sees very little erosion, the surface stays oxidized.
Hope that helps.